The present invention relates to a method of refurbishing a quartz glass component, in which the state of an attachment film of by-products (hereinafter called the “deposit”), erosion and deterioration of a quartz glass component that has been spent by using in a certain process of semiconductor manufacturing, for example, is carefully checked before cleaning the quartz glass component, an appropriate cleaning method is determined depending on the contamination status, the quartz glass component is cleaned with minimum damage to a base material, the residual deposit is precisely checked to thereby carefully select the quartz glass component and carry out refurbishment rationally. As a result, the refurbishment method can increase the mechanical strength of the quartz glass component which is made of brittle material, prevent breakage arising from growth of thermal stress and strain during a flame treatment in a refurbishment process, enhance the productivity and the yield ratio through efficient use of quartz glass materials, stabilize the quality and rationalize the refurbishment.
In a plasma processing apparatus for manufacturing a semiconductor or liquid-crystal device, the surface of the quartz glass component is eroded and deteriorated by continuous use in a plasma environment that contains fluorine or chlorine-based gas. Even though the quartz glass component is regularly discarded after the predetermined amount of erosion, it is so expensive that improvement of the situation has been desired.
Due to such demand, various methods have been proposed to remove and refurbish the eroded and deteriorated portion of the quartz glass component.
For example, there has been proposed a method in which the deposit on the surface of the quartz glass component, which is to be refurbished, consists of organic matter containing fluorine and is removed by using a chemical such as dilute hydrofluoric acid or by a grinding process. After removal of the deposit, a reaction surface, which has been eroded and deteriorated in the plasma environment, and its opposite surface are thickened through welding quartz rods with an oxygen-hydrogen flame burner. Then, after grinding thickened sides into the predetermined thickness, both surfaces are finished to an original state by precision machining and cleaning. (For example, see patent document 1.)
Another refurbishing method of the quartz glass component also has been proposed. The quartz glass component with a step design on the surface, which is to be refurbished, having the reaction surface by plasma is cut near the periphery thereof, and the plate-like portion including the eroded area is separated from the outer portion with no erosion. Then, the plate-like portion with the erosion area is discarded, and is renewed with a new material that has almost the same shape as the original. The new one is welded to the separated outer portion for refurbishment. (For example, see patent document 2.)
Further, another refurbishing method of the quartz glass component has been proposed. In a quartz glass component with a step design on the surface, which is to be refurbished, a contamination layer of a plate-like portion including the eroded area is removed by a grinding process, and its surface is finished to mirror polish. Then, a new plate having almost the same shape as the plate-like portion is manufactured, and the one side of the new plate is finished to mirror polish. The mirror surface of the new plate is contacted with the mirror surface of the existing component. The contact surface is bonded by applying a high pressure to each plate and by heating in a vacuum furnace to a high temperature. (For example, see patent document 3)
However, the conventional method described above has the following problems. The surface deposit on the quartz glass component is removed by using a chemical such as dilute hydrofluoric acid or by a grinding process, and cleaning with a chemical such as dilute hydrofluoric acid is again performed to remove residual impurities before the flame treatment. Thus, the repetitive cleaning damages the surface of the base material, and significantly changes dimension and surface state of the portion in which refurbishment is not originally necessary. Moreover, it is difficult to confirm whether fine deposit remaining in microcracks on the surface of the base material has been totally removed. Thus, quality of the quartz glass component, relative to which the processing treatment is to be performed, is not uniform.
The process of the above-described refurbishment method has the following problem. Entire surfaces of the reaction surface and its opposite side is thickened by flame-welding, so that the base material is breakable due to the effect of thermal stress and strain generated in a wide area.
Moreover, there are the following problems for the refurbishment of the quartz glass component having a step design on the surface. A newly-manufactured part is welded to the whole area of the joint of the existing quartz glass component from which the contaminated portion has been separated, thereby lowering the yield ratio and use efficiency of quartz materials. Further, quartz material is breakable due to the effect of thermal stress and strain generated in the wide area, so that it requires much skill to weld the large area. Thus, such a processing treatment results in the low productivity.